Remote dual fuel changeover system with safety shutdown period



H. K. WINTERS July 1, 1969 REMOTE DUAL FUEL CHANGEOVER SYSTEM WITH SAFETY SHUTDOWN PERIOD Filed Oct. 9, 1967 xlrmotzoz 02E; N GPL I 12502 02:21 GET .ZOrEZm: N Junk T 29:29 flai 10.525 two 20 mmzmsm AAA out.

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ATTORNEYS United States Patent 3,453,061 REMOTE DUAL FUEL CHANG EOVER SYSTEM WITH SAFETY SHUTDOWN PERIOD Harry K. Winters, San Rafael, Calif., assignor to Ray Oil Burner Co., San Francisco, Calif., a corporation of Nevada Filed Oct. 9, 1967, Ser. No. 673,633 Int. Cl. F2311 /20; F23d 17/00; F23q 9/08 US. Cl. 431-29 2 Claims ABSTRACT OF THE DISCLOSURE A system for use with a dual fuel burner for remotely, and automatically if desired, changing from one fuel to another while the burner is firing and utilizing electromagnetically actuated relays or equivalent devices with means to insure that the burner is completely shut down for a finite period of time after burning one fuel before it is fired with another fuel and thus prevent a dangerous possibility of burning two fuels at the same time.

There are many areas where natural gas is used as a fuel in which the demand exceeds the supply during peak use periods such for example as in very cold weather. Since gas generally speaking is less costly than oil it is common practice for it to be sold at a greatly reduced price to consumers of large quantities of fuel with the provision that they employ a dual fuel burner and maintain a standby supply of oil to be used during peak periods.

To insure that the conversion from one fuel to the other be done promptly and without reliance upon the customer, it is desirable that it be under control of the gas distributor and preferably from its place of business remote from the point of use. This can be readily accomplished with a simple electric circuit which may employ existing telephone lines or the like.

When burners are fired automatically in response to some condition such as temperature or steam pressure, a programming and monitoring device is used. Such devices are common and generally follow a sequence of operations which would be somewhat as follows:

(1) Start blower motor and operate for a purge period. (2) Start ignition (spark or pilot flame) and monitor. (3) Open main fuel valve.

Each step is dependent upon successful functioning of the former step and flame monitoring continues and causes shutdown upon flame failure. Such programming and monitoring devices are controlled by relays and contain a master relay which opens or drops out upon flame failure or satisfaction of demand to cause closing of the fuel valve and burner shutdown. Whenever this master relay has opened, the program and monitor device is caused to initiate a complete sequence of starting operations to resume burner operation. One requirement of approval authorities in many localities is that a dual fuel burner must be completely shut down and proceed through a complete starting sequence before firing with a second fuel.

3,453,061 Patented July 1, 1969 It is therefore the object of the present invention to provide a remote dual changeover system which insures complete shutdown of the burner burning one fuel before it can be changed to another fuel. Further and more specific objects and advantages of the system are made apparent in the following specifications wherein reference is made to the accompanying drawing.

The drawing is a schematic view of a system embodying the present invention.

In the drawing, the fuels are referred to as Fuel 1 and Fuel 2 rather than as oil and gas which is only one example of other fuels that might be employed alternately in the same burner. In the drawing a power source is shown at 10 and a fuel selector switch 15 controls a circuit 11 through a single pole double throw time delay relay switch 12 which includes any type of suitable delay mechanism operable both upon energizing and de-energizing and a multi pole double throw relay switch 14. The position of a switch 15 in the circuit 11 determines which of two fuels is to be used. A second circuit 16 flows through a typical automatic fuel burner program and flame monitor control shown at 18 which, through the multi pole double throw relay, is connected upon closing of a burner on-off switch 19 with the ignition, valving and monitoring devices at the burner represented generally at 20. As illustrated in the drawing, the connection is with each of these devices for Fuel 2. Only typical devices are illustrated as there might be a blower motor as well as ignition monitoring and other similar devices depending upon the particular furnace with which the invention is used.

When it is desired to change from Fuel 2 to Fuel 1, the fuel selector switch 15 is closed to energize the relays of the single pole time delay and the multi pole double throw relay. The double throw switch will act instantly to break the circuit 16 and to connect the programming device with the Fuel 1 controls at the burner. The time delay relay 12 is also energized but a short delay is imposed to break the circuit to the programmingv device and to permit the relays therein and particularly the master relay to drop out effecting shutdown of the burner. After the predetermined delay, which need be only a fraction of a second, the circuit 16 will be closed through an alternate line shown at 22 and a complete normal starting cycle will be initiated through the burner programming device.

The fuel selector switch 15 and the burner on-off switch 18 could be manually actuated switches or alternately they might be automatic switches which act in response to pressure or temperature or the like. For example, the fuel selector switch, if located in a position remote from the burner, such for example as the plant of the gas distributor, may act in response to temperature to switch fuel from gas to oil when the temperature drops below a predetermined point. In the case of the burner on-off switch whether it be located on the premises of the user or the fuel distributor it could be operable in response to temperature or in response to pressure of a steam boiler or the like.

I claim:

1. A remote dual fuel changeover system for a burner having a conventional burner programming control which includes a separate electrical program circuit for each to two fuels, a source of electrical energy, a first solenoid actuated switch means for connecting the source alternately to either program circuit, and a solenoid actuated time delay switch in series with said first solenoid actuated switch means to prevent the completion of changeover to one circuit, after initiating it, from the other for a finite time period.

2. The system of claim 1 in which the time delay is before firing of the other.

4 References Cited UNITED STATES PATENTS 1/1932 Scott 431-69 3/1955 Ray 431-29 US. Cl. X.R. 431281 

